Electro-magnet



March 21, 1961 M. GPFERT 2,976,464

ELECTRO-MAGNET Filed sept. 19, 1955 /Lsc 5y @am United States Patent O ELECTRO-MAGNET Max Gpfert, Friedrichshafen, Germany, assignor to Zahnradfabrik Friedrichshafen, Friedrichshafen am Bodensee, Germany Filed Sept. 19, 1955, Ser. No. 535,236

Claims priority, application Germany Oct. 14, 1954 2 Claims. (Cl. S17-191) The invention relates to electro-magnets and more particularly to solenoid magnets for use in machines.

It is an object of the invention to provide a magnet having a very strong pull for its bulk.

It is a further object of the invention to provide a magnet compact in size and which may be readily assembled with identical units.

It is another object of the invention to provide a magnet of simple structure and readily manufactured in mass production.

Other objects and features of the invention will be apparent from the description which follows in conjunction with the drawing, in which:

lFig. l is a longitudinal cross-section of the invention, and

=Fig. 2 is a plan view partially in section through 2-2 of Fig. 1.

Briefly, prior art electro-magnets have heretofore been made comprising cylindrical solenoids surrounded by a cylindrical casing. I have found, however, that if the casing be prismatic, for example, square in shape, in diametrc cross-section relative the cylindrical solenoid, a considerably increased pull effect is realized. This is in contradistnction to prior art constructions which rely on cylindrical casings internally and externally of a cylindrical solenoid. Thus, my structure contemplates the use of a cylindrical solenoid having an internal cylindrical casing but being externally surrounded by a casing of considerably heavier mass than is afforded by the usual cylindrical external casing, the corners of the external casing accounting for the extra mass.

Referring now to the drawings, my invention comprises a plate 4 of non-magnetic material set into the bottom of a pot-shaped casing *3 of a magnetic material. Within the casing 3 is a solenoid 5 having an internal cylindrical casing. The casing 3 is covered by a magnetic cover 6. A guiding post 2 is slidably reciprocal through plate 4 and will be understood to be integral with the plunger 1. Plunger 1 also has a post 8 extending through cover 6 and guided by means of casters 9, the post 8 being utilized for accommodating machine parts as desired. Cover 6 is provided with a conical counterbore 7 for accommodating the conically shaped upper end of plunger 1.

The casing 3 and plates 4 and 6 are maintained in assembly by means of bolts 16. Casing 3 is provided with a slit at one side thereof thru which passes rigid conductor elements 10 for bringing electric current to the coil, the elements 10 being integral with the solenoid. The other ends of the conductor elements are bolted at 14 to an insulating block 11 which is thus supported between the conductor elements. The insulating block 11 is provided with a pair of conductive studs 12 having bolts 13 to which line wires may be connected. The bolts 14 are preferably screwed into suitably provided holes in the studs 12 so as to effect secure electrical and mechanical connection.

Preferably the casters 9 are carried in individual brackets as shown and spaced apart around the post 8. The brackets are rigidly secured to the cover 6.

With a magnet constructed as disclosed above, I have found that an exceptionally strong pull can be achieved. In fact, tests have indicated that such a magnet has almost twice as much pull as a magnet constructed in accordance with the prior art using cylindrical internal and external casings wherein operating conditions as to solenoid size, current, and plunger were the same. I attribute this remarkably improved eiect to the existence of the masses of ferro-magnetic material at the corners of the prismatic external casing by virtue of the polygonal shape.

I claim:

1. An electro-magnet having a solenoid surrounded by an external casing, said casing having large masses at predetermined points distributed about the periphery of said solenoid, said solenoid being substantially totally enclosed in said casing, said casing having a polygonal, cross sectional area diametrically in a plane transverse to the axis of said solenoid, said area being diminished only by the `area of the solenoid therein within said casing, wherein said solenoid occupies the maximum possible space therein and wherein said casing has relatively thin, longitudinal walls extending between the relatively thick, generally triangular corners thereof, and a cover of magnetic material at one end, at least, of said casing to cornplete the magnetic circuit of said casing, and a magnetic plunger reciprocally movable within said solenoid.

2. An electro magnet as set forth in claim 1 wherein the polygonal cross sectional area of said casing is square.

References Cited in the le of this patent UNITED STATES PATENTS 917,017 Dean Apr. 6, 1909 1,669,753 Hoeiier May 15, 1928 2,239,312 Berges Apr. 22, 1941 2,348,055 Chapman May 2, 1944 2,353,740 Malone July 18, 1944 2,421,444 Tyne June 3, 1947 2,482,902 Clark Sept. 27, 1949 2,651,744 Acklin et al. Sept. 8, 1953 2,661,446 Adcock Dec. 1, 1953 2,665,397 Jencks lan. 5, 1954 2,718,623 Yoder et al Sept. 20, 1955 2,728,879 Erikson Dec. 27, 1955 FOREIGN PATENTS 196,453 Great Britain Apr. 26, 1923 

